Development of a magnetic recording medium that is suitable for a high recording density has beers in progress so as to improve a recording density of the magnetic recording and reproducing apparatus.
Examples of the magnetic recording medium in the related art include a magnetic recording medium in which a recording layer and the like are stacked on a substrate for a magnetic recording medium, a protective layer such as carbon is formed on the recording layer, and a lubricant layer is formed on the protective layer. The protective layer protects information that is recorded on the recording layer and enhances sliding characteristics of a magnetic head. However, it is difficult to sufficiently obtain durability of the magnetic recording medium by only providing the protective layer on the recording layer.
Therefore, typically, a lubricant is applied onto a surface of the protective layer to form a lubricant layer. When the lubricant layer is provided oil the protective layer, it is possible to prevent the magnetic head of the magnetic recording and reproducing apparatus and the protective layer from coming into direct contact with each other, and it is possible to significantly reduce a friction force of the magnetic head that slides on the magnetic recording medium. As a result, durability is improved.
As the lubricant that is used in the magnetic recording medium, a perfluoropolyether-based lubricant, an aliphatic hydrocarbon-based lubricant, and the like are suggested.
For example, Japanese Unexamined Patent Application, First Publication No. S62-66417 discloses a magnetic recording medium onto which a perfluoroalkyl polyether lubricant having a structure of HOCH2—CF2O—(C2F4O)p-(CF2O)q-CH2OH (p and q each represents an integer) is applied.
In addition, Japanese Unexamined Patent Application, First Publication No. H9-282642 discloses a magnetic recording medium onto which a perfluoroalkyl polyether (tetraol) lubricant having a structure of HOCH2CH(OH)—CH2OCH2CF2O—(C2F4O)p-(CF2O)q-CF2CH2OCH2—CH(OH)CH2OH (p and q each represents an integer) is applied.
In addition, Japanese Unexamined Patent Application, First Publication No. 2002-275484 discloses a lubricant for a magnetic recording medium which includes a perfluorooxyalkylene unit selected from —CF2O— and —CF2CF2O—, and a phosphazene compound.
In addition, Japanese Unexamined Patent Application, First Publication No. 2010-108583 discloses a configuration in which a lubricant layer obtained by mixing a phosphazene compound and a compound including a perfluorooxyalkylene unit in a specific range is used to obtain a lubricant layer having high bonding strength with the protective layer and a high coverage factor even when reducing the layer thickness of the protective layer.
In addition, Japanese Unexamined Patent Application, First Publication No. 2013-163667 discloses a lubricant that contains a compound that is expressed by R1C6H4O—CH2CH(OH)CH2OCH2—R2—CH2—O—R3.
In addition, Japanese Unexamined Patent Application, First Publication No. 2014-116060 discloses that one of ionic contaminants on a magnetic recording medium, which become a cause for occurrence of breakage or contamination in the magnetic head of the magnetic recording and reproducing apparatus, is outgas generated from a siloxane-based organic Si that is used as a rubber seal for hermetic sealing of the magnetic recording and reproducing apparatus.